초록 ▼

A well-known technique to discourage piracy of digital objects is to fingerprint the version each customer receives. The invention provides a novel way of fingerprinting the decryption functions given by broadcasters to their customers (usually in the form of smart cards). The main difficulty is to

A well-known technique to discourage piracy of digital objects is to fingerprint the version each customer receives. The invention provides a novel way of fingerprinting the decryption functions given by broadcasters to their customers (usually in the form of smart cards). The main difficulty is to ensure that all the algorithms provided by the broadcaster implement the same decryption function, and yet to make it computationally difficult for a pirate who obtains a large number of such implementations to find even one fundamentally different implementation which is not traceable to a particular customer.

대표청구항 ▼

[ What is claimed is:] [1.] A method of fingerprinting a common function in broadcast systems comprising the steps of(a) determining for each customer a unique function,(b) arranging the functions to be identical on a subset X of inputs, and different (with high probability) on other inputs, and(c)

[ What is claimed is:] [1.] A method of fingerprinting a common function in broadcast systems comprising the steps of(a) determining for each customer a unique function,(b) arranging the functions to be identical on a subset X of inputs, and different (with high probability) on other inputs, and(c) broadcasting only inputs in X in order to enable all customers to compute common outputs, whereby to enable pirate cards to be traced to particular customers by analyzing their computations on arguments which are not necessarily in X.